Scientists are reporting for the first time that previously unrecognized substances released by algae blooms have the potential to act as endocrine disruptors, which can interfere with the normal activity of reproductive hormones. The effect is not caused by microcystin toxins, long recognized as potentially harmful to humans and aquatic animals, but as yet unidentified substances. As a result, the scientists are calling for a revision of environmental monitoring programs to watch for these new substances.
University of Tennessee, Knoxville, researchers have found that blue-green algae may be responsible for producing an estrogen-like compound in the environment which could disrupt the normal activity of reproductive hormones and adversely affect fish, plants and human health. Previously, human activities were thought solely responsible for producing these impacts.
Theodore Henry and colleagues note that harmful blooms of toxin-producing algae, called cyanobacteria or blue-green algae, occur in waters throughout the world and are a growing health and environmental concern. The algae produce microcystins that can harm fish, plants, and human health.
"The induction of these genes is consistent with presence of an estrogen and it is possible that many adverse affects may occur in fish populations," said Henry, "from physical feminization of male fish to behavioral changes, increased environmental estrogen levels can impact male territorial defending and even their nest-building habit. Environmentally released estrogen has not been shown to affect reproduction, but studies are still being conducted on the subject."
Possible human health effects include skin rashes, fever and liver damage. Henry and colleagues note that harmful blooms of toxin-producing algae occur in waters throughout the world and are a growing health and environmental concern. As a result, the scientists are calling for a revision of environmental monitoring programs to watch for these new substances.
In an effort to find out, Emily Rogers supervised by Theodore Henry, and co-authors Michael Twiner, Julia Gouffon, Jackson McPherson, Gregory Boyer, Gary Sayler, and Steven Wilhelm turned to zebrafish, often used as a stand-in for people and other animals in laboratory experiments. They found that something released by algae, other than microcystins, had an endocrine disrupting effect on the fish. The report recommends that environmental protection agencies may need to update monitoring programs for algae blooms to include potential endocrine-disrupting substances.
The scientists acknowledge funding from the National Oceanic and Atmospheric Administration.
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